SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab977e3e4a8df8213716e86f06a1453357758e6714c838f766a399cab55bd35e' 
  AND token = '12zm4BrFOi1CfsF0sn7gnYRXZLjiBQb+SCF2csAuLuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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