SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c828967653cec6a7ffd8ba4976a9239b436a03640d00628d999f0630c832d978' 
  AND token = 'h1c7FG6EMyWYrzvzpsUtFzPrehScBDbksdGZGLp/onk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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