SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7a576e499d7bf3787ed0344a2aadf521adda989b4323c1828595af569962d6b' 
  AND token = 'y13V1/GAHvkUCpI2d7XZvlSkOo5AtHZQBw+kgfIArOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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