SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51e6a08d11290e066616689ca4f3adf2dab989c0e81ae9fc7e301df9732a81d3' 
  AND token = 'DJQJn9s/7+T5ibwj+NDfr87DhQL4I8TBM7y2GimCeck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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