SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8df50bcee6f880a65d316469604a374d11291348895d955211c30a371c1e7ed' 
  AND token = 'R98AmCLNq7flpQDOCKsyYYsrlpyCvNxRRp4g/dV6m8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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