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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7bf2e331a8409d691728d40365e9822c8354a2bd48f4aecc0a2054560c74dcc' 
  AND token = 'phc1+bCNTnbIeYYSuzlaA7lxHmP/KCfXQpN7oQhOZ1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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