SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7974d2fdf7a92f7eefb614271ef63f0935ada109042902c27a422b104aede2ba' 
  AND token = 'rc54MPDAuBPNNkTA+2OPgrGGO98UkbMGe3naXdANBzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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