SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2088d7902935622df99ea598eb65e668a1836be1a01f813ce417ed65407493bf' 
  AND token = 'RXIoR3+hCg+6+BTQvje3SNI+KdGPQ2egdQxRbYSKCS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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