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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff0847ff0f7dd0f1c09e4eb2385d91958c5882961dacad8480b3e99ea6ce51d8' 
  AND token = 'RhRMhqgPmTB+b2X1FHUGP3KBMbdTkfxEzvNIRHCKnrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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