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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8ea8999825021059cf30e333ae7793a135a19b92eed01c9296b9dfcbd2ee9b' 
  AND token = 'TwCQACFrMAUgxCna6vxvQsdo5NKQbjepwUmN5f9uo2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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