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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecf0cf48aec5b502f4b6af46399e0cc958c5e8c9829edf476a9e3b77d55d8e42' 
  AND token = 'mr1n2dgWRMSZXz0Ss6p+HT6HT2vsDMyIzGerCYTB50U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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