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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6939c5f738101c70f1dd8c65cc8fbec3ea1d204ade552e5ac6959bd6d98fabc' 
  AND token = 'nAkeXW+dk64eeBAiH/xUWVCy3zsruiSMTEaSoa3hEIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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