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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd60638bf003b7cb0ab2cd9c1ac0b688f45678b86a549ef1223beaaaddb75c0b5' 
  AND token = 'Na1xm+/VyxczQVhEOPghpMTNIKnwQ6rtDN2pBWDiaB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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