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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e70319e3c3fa49fe36757f1fd7327261dadb334ad186a18f5f9100fe71c5f19d' 
  AND token = '6g5NeW4fTcaa1AzXFF8OVVpS9Ic+LsUCdxvGdpYsRGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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