SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47dfdf9d528bf762de38d1baefcb2bf31c52f6ac147a79854cf76a62900be9f1' 
  AND token = 'Qn42IfPsJcncp+rYF0/0xYgeJdFi6FdJlekL3mP4Irs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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