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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12d986ebcd7c46949e7dd76e0af3ee8d004f62df7d3fc18e670471a5a2e4c331' 
  AND token = 'gYgFcjsa6emJMePaNq2dhTBcRPZN9fCxsoM3x1LirV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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