SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b38a379049b250c8ef7792a522065725e52135bc2a6ac027c1a22e2565cb8123' 
  AND token = 'v+fOeCe6+Fbb2WLA81cYvrSTK5UAF+pEiS8oOUvKsG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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