SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30f90bfdb76effa61453880e3aeb752d1967744ff0a219f23060f3fdc44a7632' 
  AND token = 'UOgqq+gGAkfRAomtxU4Ny2dN09ImmsIbLTSqc1jk5i0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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