SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd53f2be1334722c10efd60644d1d52651e59d698b33676756878076404b43e4a' 
  AND token = 'T+yFtjiM0qbSVygPxy6dK+3w50H/oBP4w4fUPED7AVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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