SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6f323dafb79822d63ae7f147611b5a12fd64aabc81517717bda0d941418eb1b' 
  AND token = '8xWUw+mOX0Bcn2AZcuurrnG+xpbL/7cfXwa4B2Jkb6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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