SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '638c8b09b134bd5192ba91d16fce952bcf8f82f51e44f6795532679e8b7ff41c' 
  AND token = '4/yBIXWTKr+NFNdTWTuqJygvFS4OzQathzwSoqjwxK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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