SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2d3a5bdbb5c09901582b6f1bdd5fb764ef6a1a1ee28bd1de7fbec40bcc408b9' 
  AND token = 'w5ZckRT+49ZlPvtLsqG+8B77tM+z/s1vVVJkWFzQ/Fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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