SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '83595931ce7fce9d44755a41d72c5136a2ca1d4a2960160b746925db12535592' 
  AND token = 'HbeZuj6zVqIsSsI/sCnt+gDjbC3r2xMCm67wDGGxeX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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