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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50134147d6ab298fcbb5cd7ffc3e1d09f0d6a5a7eeea9c6c5c9b16301d738cf' 
  AND token = 'B47NGTe+3P/OBDE9d5seqr44q/lg5isxU5+gcTBPtU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}