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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1dbedab6ded8b1ee3b7a5ba403b94577fbd4eb39d8eeb988a37dc20555c698a' 
  AND token = 'q0iI9iW3IwiILlmQ81/BkrgZyqYg87FcxYxMAPLzy4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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