SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cace4d6710bba54094af57a4b0a03edfe3a7a81f6f5e1c7335c0e60513e839a3' 
  AND token = '1B40Bh5QdQPT2YvT01UUZKQf7oAR8ygq0+tsGlXvR30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}