SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '575918dd46ab76450182411de8cbb55700253c9dce3aacd7d27413cca16e452c' 
  AND token = 'qV3pfmjBw3fvxkV5tVghlbBr2bZjCPhHKjkRLN2aTjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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