SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '592416f4b2f6fa1a7d93494437a61030820da8be6cca2297786f9f574d285ac9' 
  AND token = 'J/KLw8kFtnYvp+5LWlceM9LcALHp1p3GuIfRbS8o2BY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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