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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2ccc5f5e843c6515fd0b32b18295664c0a9a645e6a959895d55a7380b2df6a5' 
  AND token = 'n8ZPkqIWBoBBSdASAG/E9CUqtHfBTYSLqPUh1hc5Zqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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