SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '581891f3adb374e168b44acd1018ba9393b22bac6ec95677a1492800ffdb753c' 
  AND token = 'xqS8/v1SGAoF08comcIPf0jl2uTByFkR8g8Kj+GVrLQ=' 
  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"
    }
  }
}