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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af7b950e0d3369baf339d7c8f406c3da6ff21166166ea601b273cd388df396d3' 
  AND token = '9z9pXvGG+nNIP8W62q3S7nEczH74gadzXwsN1O10uyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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